Method and apparatus for metering catalyst in a fluid catalytic cracking catalyst injection system

ABSTRACT

A method and apparatus for metering catalyst in a fluid catalytic cracking catalyst injection system are provided. In one embodiment, apparatus for metering catalyst in a fluid catalytic cracking catalyst injection system includes a low pressure storage vessel coupled to a pressure vessel that defines a high pressure side of the apparatus, where the determination of the amount of catalyst transferred is made on the low pressure side of the apparatus.

RELATED APPLICATIONS

[0001] This application is related to U.S. patent application Ser. No.10/304,670, filed Nov. 26, 2002, and U.S. patent application Ser. No.10/320,064, filed Dec. 16, 2002, both of which are hereby incorporatedby reference in their entirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] Embodiments of the invention generally relate to a method andapparatus for metering catalyst in a fluid catalytic cracking catalystinjection system and the like.

[0004] 2. Description of the Related Art

[0005]FIG. 1 is a simplified schematic of one embodiment of aconventional fluid catalytic cracking system 130. The fluid catalyticcracking system 130 includes a fluid catalytic cracking (FCC) unit 110coupled to a catalyst injection system 100, an oil feed stock source104, an exhaust system 114 and a distillation system 116. One or morecatalysts from the catalyst injection system 100 and oil from the oilfeed stock source 104 are delivered to the FCC unit 110. The oil andcatalysts are combined to produce an oil vapor that is collected andseparated into various petrochemical products in the distillation system116. The exhaust system 114 is coupled to the FCC unit 110 and isadapted to control and/or monitor the exhausted byproducts of the fluidcracking process.

[0006] The catalyst injection system 100 may include a main catalystinjector 102 and one or more additive injectors 106. The main catalystinjector 102 and the additive injector 106 are coupled to the FCC unit110 by a process line 122. A fluid source, such as a blower or aircompressor 108, is coupled to the process line 122 and providespressurized fluid, such as air, that is utilized to carry the variouspowdered catalysts from the injectors 102, 106 through the process line122 where they are combined with oil from the oil feed stock source 104and delivered into the FCC unit 110.

[0007]FIG. 2 is one embodiment of a conventional additive injector 106.The additive injector 106 includes a pressure vessel 220 and a lowpressure storage vessel 240. The pressure vessel 220 is coupled to oneor more load cells 210 for weighing the catalyst that will be introducedinto the FCC unit 110 through the process line 122. In operation, thecatalyst is dispensed into the pressure vessel 220 at atmosphericpressure from the low pressure storage vessel 240. The pressure vessel220 is subsequently weighed to determine the amount of catalyst loadedtherein. The pressure vessel 220 is then pressurized by a pressurecontrol device 228 coupled to the vessel 220 to a level that facilitatesmovement of the pressurized catalyst into process line 122 and then intothe FCC unit 110. If the pressure vessel 220 is supported by any of thestructural components surrounding it, other than the load cells 210(such as pipes, electrical conduits, and the like), those componentswill prevent the load cells 210 from accurately measuring the weight ofcatalyst added to the pressure vessel 220, and ultimately into the FCCunit 100. Therefore, in order to obtain a reasonably accurate measure ofthe catalyst, the pressure vessel 220 must not be supported by othercomponents of the system.

[0008] To isolate the pressure vessel 220 from the components coupledthereto, flexible connectors, such as bellows 230, are used to couplethe pressure vessel 220 to the low pressure vessel 240, the process line122, and other surrounding components. The bellows 230 allow thepressure vessel 220 to “float” on the load cells 210 so a more accuratereading may be obtained. However, use of flexible bellows 230 does notreliably insure accurate weight measurement of the pressure vessel 220.For example, the weight of the pressure vessel 220 is still slightlysupported by the flexible bellows 230—a problem compounded by the factthat a plurality of bellows 230 must be utilized to isolate the pressurevessel 220 from the various components coupled thereto. Therefore, thedetermination of the weight of the catalyst added to the pressure vessel220 is still not accurate. Moreover, due to the operating pressures andpotentially explosive atmosphere, bellows meeting operational standardsare quite expensive and wear quickly, resulting in the drift of weightreadings, catalyst dust leaks and associated environmental issues, aswell as necessitating costly process downtime and bellows replacement.

[0009]FIG. 3 is another embodiment of an additive injector 300. Theinjector 300 includes a high pressure storage vessel 340 coupled by ametering valve 330 to the process line 122. The metering valve 330 maybe actuated to allow a predefined amount of catalyst to be introducedinto the process line 122 and combine with the oil from the oil feedstock source 104 before entering the FCC unit 110. The high pressurestorage vessel 340 contains a bulk supply of catalyst, for example, fromabout 1 to about 20 tons of catalyst, and is maintained at a pressurebetween about 50 to about 60 pounds per square inch (psi) by a pressurecontrol device 320. As such, the pressure vessel 340 is subject toregulatory construction standards which cause the vessel to berelatively expensive as compared to a comparably sized, low pressurestorage vessel. The high pressure vessel 340 is coupled to a pluralityof load cells 310 which enable the weight of the high pressure storagevessel 340 to be determined. The weight of the catalyst injected isdetermined by comparing the weight of the high pressure storage vessel340 before and after catalyst injection.

[0010] Metering catalyst in the manner described with reference to FIG.3 eliminates the need for bellows used to isolate the pressure vessel.However, large high pressure storage vessels are very expensive.Therefore, there is a need for a method and apparatus for meteringcatalyst in a fluid catalytic cracking catalyst injection system thatminimizes the cost of ownership.

SUMMARY OF THE INVENTION

[0011] A method and apparatus for metering catalyst in a fluid catalyticcracking catalyst injection system are provided. In one embodiment,apparatus for metering catalyst in a fluid catalytic cracking catalystinjection system includes a low pressure storage vessel coupled to apressure vessel that defines a high pressure side of the apparatus wherethe determination of the amount of catalyst transferred is made on thelow pressure side of the apparatus.

DESCRIPTION OF THE DRAWINGS

[0012] So that the manner in which the above recited features of thepresent invention are attained and can be understood in detail, a moreparticular description of the invention, briefly summarized above, maybe had by reference to the embodiments thereof which are illustrated inthe appended drawings. It is to be noted, however, that the appendeddrawings illustrate only typical embodiments of this invention and aretherefore not to be considered limiting of its scope, for the inventionmay admit to other equally effective embodiments.

[0013]FIG. 1 is a simplified schematic view of a conventional fluidcatalytic cracking system;

[0014]FIG. 2 is a simplified elevation view of one embodiment of aconventional catalyst injector having a low pressure storage vessel;

[0015]FIG. 3 is a simplified elevation view of another embodiment of aconventional catalyst injector having a high pressure storage vessel;

[0016]FIG. 4 is a simplified elevation view of a fluid catalyticcracking system illustrating a catalyst metering system in accordancewith one embodiment of the present invention;

[0017]FIG. 5 is a simplified elevation view of a fluid catalyticcracking system illustrating a catalyst metering system in accordancewith another embodiment of the present invention;

[0018]FIG. 6 is a flow diagram representing an inventive method formetering catalyst in a fluid catalytic cracking system;

[0019]FIG. 7 is a simplified elevation view of a fluid catalyticcracking system illustrating a catalyst metering system in accordancewith another embodiment of the invention; and

[0020]FIG. 8 is a simplified elevation view of a fluid catalyticcracking system illustrating a catalyst metering system in accordancewith another embodiment of the present invention.

[0021] To facilitate understanding, identical reference numerals havebeen used, wherever possible, to designate identical elements that arecommon to the figures.

DETAILED DESCRIPTION

[0022]FIG. 4 depicts one embodiment of a fluid catalytic cracking (FCC)system 400 comprising an injection system 402 and oil feed stock source450 coupled to an FCC unit 424. The FCC unit 424 is adapted to promotecatalytic cracking of petroleum feed stock provided from the source 450and may be configured in a conventional manner. The injection system 402is coupled to the FCC unit 424 and is configured to inject one or morecatalysts into the FCC unit 424 to control processing attributes such asthe ratio of products recovered in a distiller of the FCC unit 424and/or to control the emissions from the FCC unit 424. The injectionsystem 402 includes a control module 404 to control the rates and/oramounts of catalyst provided to the FCC unit 424 by the injection system402.

[0023] The control module 404 has a central processing unit (CPU) 460,memory 462, and support circuits 464. The CPU 460 may be one of any formof computer processor that can be used in an industrial setting forcontrolling various chambers and subprocessors. The memory 462 iscoupled to the CPU 460. The memory 462, or computer-readable medium, maybe one or more of readily available memory such as random access memory(RAM), read only memory (ROM), floppy disk, hard disk, or any other formof digital storage, local or remote. The support circuits 464 arecoupled to the CPU 460 for supporting the processor in a conventionalmanner. These circuits include cache, power supplies, clock circuits,input/output circuitry, subsystems, and the like. In one embodiment, thecontrol module 404 is a programmable logic controller (PLC), such asthose available from GE Fanuc. However, from the disclosure herein,those skilled in the art will realize that other control modules such asmicrocontrollers, microprocessors, programmable gate arrays, andapplication specific integrated circuits (ASICS) may be used to performthe controlling functions of the control module 404. One control module404 that may be adapted to benefit from the invention is described inthe previously incorporated U.S. patent application Ser. Nos. 10/304,670and 10/320,064.

[0024] In one embodiment, the injection system 402 includes a storagevessel 440 coupled to a metering device 408. The metering device 408 iscoupled to the control module 404 so that an amount of catalystdelivered to the FCC unit 424 may be monitored and/or metered. Thestorage vessel 440 is a container adapted to store catalyst therein atsubstantially atmospheric pressures and has an operational pressure ofbetween about zero to about 30 pounds per square inch. The storagevessel 440 has a fill port 442 and a discharge port 434. The dischargeport 434 is typically positioned at or near a bottom of the storagevessel 440.

[0025] The metering device 408 is coupled to the discharge port 434 tocontrol the amount of catalyst transferred from the storage vessel 440to the pressure vessel 420 through a catalyst delivery line 414. Themetering device 408 may be a shut-off valve, rotary valve, mass flowcontroller, pressure vessel, flow sensor, positive displacement pump, orother device suitable for regulating the amount of catalyst dispensedfrom the storage vessel 440 into the pressure vessel 420 for injectioninto the FCC unit 424. The metering device 408 may determine the amountof catalyst supplied by weight, volume, time of dispense, or by othermeans. Depending on the catalyst requirements of the FCC system 400, themetering device 408 may be configured to provide from about 5 to about4000 pounds per day of additive-type catalysts (process controlcatalyst) or may be configured to provide from about 1 to about 20 tonsper day of main catalyst. The metering device 408 typically deliverscatalysts over the course of a planned production cycle, typically 24hours, in multiple shots of predetermined amounts spaced over theproduction cycle. However, catalysts may also be added in an “as needed”basis. In the embodiment depicted in FIG. 4, the metering device 408 isa control valve 432 that regulates the amount of catalyst delivered fromthe storage vessel 440 to the FCC unit 424 by a timed actuation. Controlvalves suitable for use as a metering device are available from InterCatEquipment Inc., located in Sea Girt, N.J.

[0026] The injection system 402 may also include one or more sensors forproviding a metric suitable for determining the amount of catalystpassing through the metering device 408 during each transfer of catalystto the pressure vessel 420. The sensors may be configured to detect thelevel (i e., volume) of catalyst in the storage vessel 440, the weightof catalyst in the storage vessel 440, the rate of catalyst movementthrough the storage vessel 440, discharge port 434, metering device 408,and/or catalyst delivery line 414, or the like.

[0027] In the embodiment depicted in FIG. 4, the sensor is a pluralityof load cells 410 adapted to provide a metric indicative of the weightof catalyst in the storage vessel 440. The load cells 410 arerespectively coupled to a plurality of legs 438 that support the storagevessel 440 above a mounting surface 430. Each of the legs 438 has one ofthe plurality of load cells 410 coupled thereto. From sequential datasamples obtained from the load cells 410, the control module 404 mayresolve the net amount of transferred catalyst after each actuation ofthe metering device 408 (e.g., the control valve 432). Additionally, thecumulative amount of catalyst dispensed over the course of theproduction cycle may be monitored so that variations in the amount ofcatalyst dispensed in each individual cycle may be compensated for byadjusting the delivery attributes of the metering device 408, forexample, by changing the open time of the control valve 432 to allowmore (or less) catalyst to pass therethrough and into the pressurevessel 420 for ultimate injection into the FCC unit 424.

[0028] Alternatively, the sensor may be a level sensor (not shown)coupled to the storage vessel 440 and adapted to detect a metricindicative of the level of catalyst within the storage vessel 440. Thelevel sensor may be an optical transducer, a capacitance device, a sonictransducer or other device suitable for providing information from whichthe level or volume of catalyst disposed in the storage vessel 440 maybe resolved. By utilizing sensed differences in the levels of catalystdisposed within the storage vessel 440 between dispenses, the amount ofcatalyst injected may be resolved for a known storage vessel geometry.

[0029] Alternatively, the sensor may be a flow sensor (not shown)adapted to detect the flow of catalyst through one of the components ofthe catalyst injection system 402. The flow sensor maybe a contact ornon-contact device and may be mounted to the storage vessel 440 or thecatalyst delivery line 414 coupling the storage vessel 440 to thepressure vessel 420. For example, the flow sensor may be a sonic flowmeter or capacitance device adapted to detect the rate of entrainedparticles (i.e., catalyst) moving through the catalyst delivery line414.

[0030] Although the injection system 402 described above is shownconfigured to provide catalyst from a single low pressure storage vessel440, the invention contemplates utilizing one or more injection systemscoupled to the FCC unit 424 to introduce multiple catalysts from aplurality of storage vessels. Each of these injection systems may becontrolled by either common or independent control modules.

[0031] The pressure vessel 420 is rigidly coupled to the mountingsurface 430, as load cells are not needed to determine the weight of thepressure vessel 420. The term “rigidly” is to include mounting devices,such as vibration dampers and the like, but to exclude mounting devicesthat “float” the pressure vessel to facilitate weight measurementthereof. The pressure vessel 420 has an operational pressure of about 0to about 100 pounds per square inch, and is coupled to a fluid source406 by a first conduit 418. The first conduit 418 includes a shut-offvalve 416 that selectively isolates the fluid source 406 from thepressure vessel 420. A second conduit 422 couples the pressure vessel420 to the FCC unit 424 and includes a second shut-off valve 426 thatselectively isolates the pressure vessel 420 substantially from the FCCunit 424. The shut-off valves 416 and 426 are generally closed to allowthe pressure vessel 420 to be filled with catalyst from the storagevessel 440 at substantially atmospheric pressure.

[0032] Once the catalyst is dispensed into the pressure vessel 420, thecontrol valve 432 is closed and the interior of the pressure vessel 420is pressurized by a pressure control system 428 to a level thatfacilitates injection of the catalyst from the pressure vessel 420 intothe FCC unit 424, typically at least about 20 pounds per square inch.After the loaded pressure vessel 420 is pressurized by the pressurecontrol system 428, the shut-off valves 416 and 426 are opened, allowingair or other fluid provided by the fluid source 406 to enter thepressure vessel 420 through the first conduit 418 and carry the catalystout of the pressure vessel 420 through the second conduit 422 to the FCCunit 424. In one embodiment, the fluid source 406 provides air at about60 to about 100 psi (about 4.2 to about 7.0 kg/cm2).

[0033] In operation, the injection system 402 periodically dispenses andinjects a known quantity of catalyst into the FCC unit 424. Catalyst isfilled into the low pressure storage vessel 440 through the fill port442 located in an upper portion of the storage vessel 440. The weight ofthe storage vessel, including any catalyst residing therein, is obtainedby interpreting data obtained from the load cells 410.

[0034] In one embodiment, a predefined quantity of catalyst in thestorage vessel 440 is transferred into the pressure vessel 420 byselectively opening the control valve 432 for a defined amount of time.After the catalyst has been transferred, the weight of the storagevessel 440 is obtained once again, and the exact quantity of catalystadded determined by subtracting the current weight from the previousmeasurement. Once the catalyst is transferred to the pressure vessel420, the pressure inside the pressure vessel 420 is elevated by thepressure control system 428 to, typically, at least about 20 psi. Afteroperating pressure is reached, valves 416 and 426 are opened. Thisallows fluid supplied by the fluid source 406, typically air atapproximately 60 psi, to flow through the pressure vessel 420 and carrythe catalyst to the FCC unit 424.

[0035] This metering system is advantageous over the prior art innumerous respects. For example, bulk storage of the catalyst at highpressure is not required, thereby allowing the storage vessel 440 to befabricated less expensively as compared to pressurized bulk storagecontainers of some conventional systems. Furthermore, as thedetermination of the amount of catalyst being dispensed is made at thelow pressure side of the system 402 (e.g., in the low pressure storagevessel or conduit between the storage vessel and pressure vessel), thepressure vessel 420 does not need to be isolated by bellows in order toobtain catalyst weight information, allowing for more accurate weightreadings as well as a more robust and less costly system.

[0036]FIG. 5 depicts another embodiment of a fluid catalytic cracking(FCC) system 500 comprising an injection system 502 and oil feed stocksource 450 coupled to an FCC unit 424. The injection system 502 isadapted to provide multiple catalysts to the FCC unit 424. The injectionsystem 502 includes a control module 404 for controlling the ratesand/or amounts of catalyst provided to the FCC unit 424 by the injectionsystem 502, a fluid handler 406 for injecting the catalyst into the FCCunit 424, and a pressure vessel 420 coupled to a plurality of storagevessels, illustratively shown in one embodiment as a first low pressurestorage vessel 440 and a second low pressure storage vessel 510. It iscontemplated that any number of low pressure storage vessels may becoupled to a single pressure vessel 420 for injection catalyst at ahigher pressure.

[0037] The storage vessels 440, 510 may be configured to deliver thesame or different catalysts to the FCC unit 424 and operatesubstantially similar to storage vessel 440, described above. Thestorage vessels 440, 510 are coupled to a manifold 530 which directs theplurality of catalysts to a common catalyst delivery line 414 fordelivery into the pressure vessel 420. Alternately, each storage vessel440, 510 can be independently coupled to the pressure vessel 420. Eachstorage vessel 440, 510 is coupled to an independent metering device432, 520 which controls the amount of catalyst delivered from eachstorage vessel 440, 510 to the pressure vessel 420 for injection intothe FCC unit 424. In one embodiment, the metering device 520 isconfigured similar to the metering device 432 described above. In thisconfiguration, the system 502 is capable of sequentially providingcatalyst from a predefined one of the storage vessels 440, 510, oralternatively, blending measured amounts from each storage vessel 440,510 in the pressure vessel 420 for injecting into the FCC unit 424 in asingle shot.

[0038]FIG. 6 depicts a flow diagram of one embodiment of a method 600for metering catalyst in a FCC catalyst injection system. The method 600is generally stored in the memory of the control module 404, typicallyas a software routine. The software routine may also be stored and/orexecuted by a second CPU (not shown) that is remotely located from thehardware being controlled by the control module 404. Although the method600 is discussed as being implemented as a software routine, some of themethod steps that are disclosed therein may be performed in hardware aswell as by the software controller, or manually. As such, the inventionmay be implemented in software as executed upon a computer system, inhardware as an application specific integrated circuit, or other type ofhardware implementation, manually, or a combination of software,hardware, and/or manual steps.

[0039] The method 600 begins at step 602 where the catalyst is meteredfrom a low pressure storage vessel 440 to a pressure vessel 420. In thisstep, the metering and determination of catalyst transferred to thepressure vessel 420 is performed outside the pressure vessel 420 by themetering device 408. For example, in the embodiment depicted in FIG. 4,step 602 is performed by the combination of the metering device 408 andthe load cells 410 supporting the storage vessel 440 being utilized todetermine the amount of catalyst transferred to the pressure vessel 420.The catalyst is dispensed from the storage vessel 440 into the pressurevessel 420 by temporarily opening the control valve 432. The weight ofthe storage vessel 440 is measured both before and after dispensing thecatalyst by interpreting the output of the load cells 410 coupled to thelegs 438 which support the storage vessel 440. The amount of catalysttransferred to the pressure vessel 420 is the difference between theweight of the storage vessel 440 before and after dispensing thecatalyst. Alternatively, as discussed above, the catalyst meteringdevice 408 may be a shut-off valve, rotary valve, mass flow controller,pressure vessel, flow sensor, positive displacement pump, or otherdevice suitable for regulating the amount of catalyst dispensed from thestorage vessel 440 for delivery to the FCC unit 424.

[0040] At step 604, the pressure vessel 420 containing the catalyst ispressurized by the pressure control system 428 to between about 10 toabout 100 pounds per square inch. At step 606, the pressurized catalystis injected into the FCC unit 424. In this step, valves 416, 427 openwhich allow the catalyst to be carried to the FCC unit 424 in a streamof fluid provided by the fluid source 406. In the embodiment depicted inFIG. 4, the pressure vessel 420 is pressurized to at least about 10 psiby the pressure control system 428. Once the pressure has been reached,valves 416 and 426 are opened, allowing the fluid in the first andsecond conduits 418, 422 to carry the catalyst into the FCC unit 424.

[0041]FIG. 7 depicts a flow diagram of one embodiment of a method 700for metering catalyst in a FCC catalyst injection system. The method 700begins at step 702 where a first catalyst is dispensed from a first lowpressure storage vessel 440 to a pressure vessel 420 using a meteringdevice 432, wherein the metering device determines the quantity of thefirst catalyst dispensed with respect to the first storage vessel. Atstep 704, the pressure vessel 420 containing the first catalyst ispressurized. Then, at step 706, the pressurized catalyst is injectedinto a FCC unit 424.

[0042] The method continues at step 708, where a second catalyst ismetered from a second low pressure storage vessel 510 to the pressurevessel 420 using a metering device 520, wherein the metering devicedetermines the quantity of the second catalyst dispensed with respect tothe second storage vessel. At step 710, the pressure vessel 420containing the second catalyst is pressurized and finally, at step 712,the pressurized second catalyst is injected into the FCC unit 424. Themethod 700 contemplates the use of additional low pressure vessel whichload the pressure vessel 420 in a predefined order, or as needed.

[0043]FIG. 8 depicts a flow diagram of one embodiment of a method 800for metering catalyst in a FCC catalyst injection system. In thismethod, beginning at step 802, a first catalyst is metered from a firstlow pressure storage vessel 440 to a pressure vessel 420 using ametering device 432, wherein the metering device determines the quantityof the first catalyst dispensed with respect to the first storagevessel. At step 804, a second catalyst is metered from a second lowpressure storage vessel 510 to the pressure vessel 420 using a meteringdevice 520, wherein the metering device determines the quantity of thesecond catalyst dispensed with respect to the second storage vessel. Atstep 806, the pressure vessel 420 containing the first and secondcatalysts is pressurized and at step 808, the pressurized catalysts areinjected into the FCC unit 424 as a single shot of catalyst. The method800 contemplates the use of additional low pressure vessels which mayprovide mixtures of different catalyst as needed or per a predefinedprocess sequence.

[0044] The methods described in FIGS. 7 and 8 allow for multiplecatalysts to be injected into the FCC unit as needed. For example, onecatalyst may control emissions from the cracking process and anothercatalyst may control the resultant product mix produced by the FCC unit.This allowed greater process flexibility with reduced capitalexpenditures.

[0045] Thus, an injection system has been provided that facilitates moreaccurate metering of catalyst and reduces problems associated withbellows used in some injection systems of the prior art. Moreover, theinventive system is compatible with existing low pressure storagevessels and does not require expensive bellows to isolate the pressurevessel. Therefore the inventive system is substantially less expensivethan the injection systems of the prior art.

[0046] Although the teachings of the present invention have been shownand described in detail herein, those skilled in the art can readilydevise other varied embodiments that still incorporate the teachings anddo not depart from the scope and spirit of the invention.

What is claimed is:
 1. Apparatus for metering catalyst in a fluidcatalytic cracking catalyst injection system, comprising: a low pressurestorage vessel; a pressure vessel rigidly coupled to a supportingsurface having an outlet adapted to be coupled to a fluid catalyticcracking unit and an inlet; and a metering device coupling the storagevessel to the inlet of the pressure vessel.
 2. The apparatus of claim 1,further comprising: at least one load cell adapted to provide a metricindicative of a weight of the storage vessel.
 3. The apparatus of claim2, wherein the metering device comprises: a control valve coupled to adischarge port in the storage vessel.
 4. The apparatus of claim 3,further comprising: a control module coupled to the control valve andthe at least one load cell, wherein the control module is adapted tocontrol the operation of the control valve based at least in part uponthe interpretation of signals received from the load cells.
 5. Theapparatus of claim 1, wherein the metering device comprises: adispensing device; and at least one sensor adapted to provide a metricfrom which the amount of catalyst transferred from the low pressurestorage vessel to the pressure vessel through the dispensing device maybe resolved.
 6. The apparatus of claim 5, wherein the dispensing deviceis at least one of a shut-off valve, rotary valve, or positivedisplacement pump.
 7. The apparatus of claim 5, wherein the sensor is atleast one of a optical transducer, capacitance device, sonic transducer,mass flow controller, or load cell.
 8. The apparatus of claim 1, furthercomprising: a pressure control device rigidly coupled to the pressurevessel and capable of increasing the pressure within the pressure vesselabove at least 10 pounds per square inch.
 9. The apparatus of claim 1,further comprising: a fluid source rigidly coupled to the pressurevessel.
 10. The apparatus of claim 1, further comprising: a second lowpressure storage vessel; and a second metering device coupling thestorage vessel to the pressure vessel.
 11. Apparatus for meteringcatalyst in a fluid catalytic cracking catalyst injection system,comprising: a low pressure storage vessel; a pressure vessel having anoutlet adapted to be coupled to a fluid catalytic cracking unit; acontrol valve coupling a discharge port in the storage vessel to aninlet port of the pressure vessel; and at least one load cell adapted toprovide a metric indicative of a weight of the storage vessel.
 12. Theapparatus of claim 11, further comprising: a pressure control devicerigidly coupled to the pressure vessel and capable of increasing thepressure within the pressure vessel above at least 10 pounds per squareinch; and a fluid source rigidly coupled to the pressure vessel.
 13. Theapparatus of claim 11, further comprising: a second low pressure storagevessel; and a second metering device coupling the storage vessel to thepressure vessel.
 14. A method for metering catalyst in a fluid catalyticcracking catalyst injection system, the method comprising: meteringcatalyst from a low pressure storage vessel to a pressure vessel using ametering device, wherein the metering device determines the quantity ofcatalyst dispensed with respect to the storage vessel; pressurizing thepressure vessel to at least about 10 pounds per square inch; andinjecting the pressurized catalyst from the pressure vessel into a fluidcatalytic cracking unit.
 15. The method of claim 14, wherein thepressurizing step further comprises: increasing the pressure within thepressure vessel from substantially atmospheric pressure to a pressure inthe range of from about 10 to about 100 pounds per square inch.
 16. Themethod of claim 14, wherein the metering step further comprises:obtaining data from one or more load cells coupled to the low pressurevessel; and calculating a change in the amount of catalyst disposed inthe low pressure vessel using the data.
 17. The method of claim 16,wherein the calculating step further comprises: determining a firstweight of the storage vessel prior to metering; and comparing the firstweight to a second weight of the storage vessel after the metering. 18.The method of claim 14, wherein the metering step further comprises:sensing a first level of the catalyst present in the storage vesselprior to the metering; and comparing the first level to a second levelof catalyst present in the storage vessel after metering.
 19. The methodof claim 18, wherein the first and second level of catalyst present inthe storage vessel is sensed by the use of one of an optical transducer,a capacitance device, or a sonic transducer.
 20. The method of claim 14,wherein the metering step further comprises: sensing the flow of thecatalyst flowing through at least one of the storage vessel, themetering device, or a conduit coupling the storage vessel to thepressure vessel.
 21. The method of claim 20, wherein the catalyst flowis sensed by at least one of a sonic flow meter, capacitance device, ormass flow controller.
 22. The method of claim 14, further comprising:metering catalyst from a second low pressure storage vessel to thepressure vessel using a second metering device.
 23. The method of claim22, wherein the step of metering from the second low pressure storagevessel occurs after the injecting step.
 24. The method of claim 23,further comprising: pressurizing the pressure vessel to at least about10 pounds per square inch; and injecting the pressurized catalyst fromthe pressure vessel into a fluid catalytic cracking unit.
 25. The methodof claim 22, wherein the step of metering from the first low pressurestorage vessel and the step of metering from a second low pressurestorage vessel are performed prior to the injecting step.
 26. A methodfor metering catalyst in a fluid catalytic cracking catalyst injectionsystem, the method comprising: determining a first quantity of catalystdisposed in a low pressure storage vessel; transferring catalyst to apressure vessel; determining a second quantity of catalyst disposed inthe low pressure storage vessel; resolving a net transferred quantity ofcatalyst utilizing the first and second quantity of catalyst;pressurizing the pressure vessel; and injecting the pressurized catalystinto a fluid catalytic cracking unit.